Figure I-8-7. Four Categories of Term PregnancyWith post-term pregnancy, perinatal mortality is increased two- to threefold. This
is a direct result of changes on placental function over time.
Management is based on two factors.
Macrosomia syndrome. In most patients, placental function continues
providing nutritional substrates and gas exchange to the fetus, resulting in a
healthy but large fetus. Cesarean rate is increased owing to prolonged or
arrested labor. Shoulder dystocia is more common with risks of fetal
hypoxemia and brachial plexus injury.
Dysmaturity syndrome. In a minority of patients, placental function
declines as infarction and aging leads to placental scarring and loss of
subcutaneous tissue. This reduction of metabolic and respiratory support to
the fetus can lead to the asphyxia that is responsible for the increased
perinatal morbidity and mortality. Cesarean rate is increased owing to
nonreassuring fetal heart rate patterns. Oligohydramnios results in umbilical
cord compression. Hypoxia results in acidosis and in utero meconium
passage.